H allen



Feb. 6, 1962 c. H. ALLEN 3,019,906

SUPPORTING STRUCTURES FOR SEWAGE CLARIFICATION UNITS Filed Aug. :5, 1959 2 Sheets-Sheet 1 INVENTOR. CZ/Fi'O/Y /z 621:

C. H. ALLEN Feb. 6, 1962 SUPPORTING STRUCTURES FOR SEWAGE CLARIFICATION UNITS Filed Aug. 3, 1959 2 Sheets-Sheet 2 W 4 5x55 T 2 5 I 7Q J J "70 )1 ll 1/ wi a. P 5 M2 2 0 4 M a W4 7 w w INVENTOR. CZ/FTO/Y b. flat/v BY WM ArraxA EY United States v This invention relates to a clarification tank of the type used for the treatment of sewage and more particularly to a supporting structure for the operating elements of such a tank.

Tanks of this type present a structural problem in the support of the elements within a clarification tank due to the large tank diameters. In many types of clarification tanks, the operating elements, flocculation chambers, walkway, etc., are supported from a diametrically extending supporting truss or bridge extending completely across the tank. In large tanks, a self-supporting truss of sulficient strength to carry all of the accessories becomes an exceedingly heavy and expensive item. Attempts have been made to relieve the trusses by providing a center post for carrying a portion of the truss load. These attempts have not been of much advantage since the weight of the operating mechanism is still carried by the truss so that an expensive structure is still necessary.

The principal object of the invention is to provide a supporting structure wherein the weight of all rotation elements and the drive mechanisms for the rotating elements will be directly supported upon a vertical central shaft or supporting column Without imposing any weight upon a truss and in which the walkway, flocculation chamber, etc., will in turn be supported upon the rotating elements and through them to the supporting column so as to eliminate the necessity for the heavy elaborate supporting truss structures at present required in tanks of this nature.

Other objects and advantages reside in the detail construction of the invention, which is designed for simplicity, economy, and efficiency. These will become more apparent from the following description.

In the following detailed description of the invention, reference is had to the accompanying drawings which form a part hereof. Like numerals refer to like parts in all views of the drawings and throughout the description.

In the drawings:

FIG. 1 is a fragmentary diametric section through a typical clarification tank showing the elements thereof mounted in accordance with the teaching of this invention;

FIG. 2. is an enlarged fragmentary horizontal section looking downward on the line 22, FIG. 1; and

FIG. 3 is a similarly enlarged fragmentary section taken on the line 33, FIG. 2.

The invention is applicable to many types of clarification tanks. For the purpose of illustration, a conventional concrete tank is illustrated at 10 having an overflow launder 52 and a conical bottom 11 inclining to a central sump 12 from which a sludge pipe 13 discharges at a controlled rate. A plurality of inclined rake arms 14, carrying spaced sludge rakes 15, rotate in close spaced relation to the bottom 11 to sweep sludge to the sump 12.

This invention relates more particularly to means for supporting the weight of the rake arms 14 and their sludge rakes and the operating mechanism for the arms in any type of clarification tank. In the clarifier illustrated, a truncated, conical stilling baflle 16 is concentrically positioned above the rake arms 14 to form a flocculation zone 1'7 into which raw water is conveyed through a raw water inlet pipe 18. A plurality of staatent O 3,019,905 Patented Feb. 6, 1962 "ice tionary flocculation paddles 19 project inwardly from the stilling baffle 16 intermediate a plurality of rotating flocculation arms 20 which are arranged to be rotated at different speed from the rake arms 14. In this type of tank, the invention also serves to support the weight of the flocculation arms 20, the stilling baffle 16, the paddles 19 and the flocculation drive mechanism within the tank 10.

The improved supporting means comprises a stationary, axially positioned, vertical, center shaft or supporting column 21 which is positioned at the center of the bottom of the sump 12 and extends vertically upward to a posi tion adjacent to, and preferably above, the water level in the tank 10, as indicated by the water line 42. A bearing cup 22 is concentrically formed, or fixedly mounted, on the top of the supporting column 21 and the lower race of a suitable anti-friction thrust bearing 23 is seated in the cup 22.

A rake drive shaft 24 extends downwardly into the upper race of the bearing 23-. A flange collar 25 is keyed, as indicated at 39, or otherwise fixedly mounted on the shaft 24 so as to rotate as a unit therewith, and the flange collar 25 rests upon and is supported by the thrust bearing 23.. A mounting flange 26 is formed on and surrounds the collar 25 fromwhich a tubular sludge shaft 27 is suspended. The upper extremity of the sludge shaft 27 is provided with a top flange 28 and suitable bolts 29 attach this flange concentrically to the mounting flange 26.

The rake arms 14 are secured to the tubular sludge shaft 27 at their axial extremities in any desired manner, such as by welding or the like, and the rake arms are supported in the proper inclined position by means of diagonal brace rods 30 and 31..

It can be seen from the above that'the rake arms 14 can be easily and freely rotated around the supporting column 21 with the entire weight of the sludge shaft 27, the rake arms 14, the rakes 15 and the brace rods 30 and 31 being completely and entirely supported upon the thrust bearing 23.

A pair of walkway beams 32, carrying a walkway plate 48, and provided with the usual hand rail 49, extend outwardly from one side of the tank 10 to a position on opposite sides of the rake drive shaft 24. Two cross channel members 33 extend between the Walkway beams 32 also an opposite sides of the rake drive shaft 24. The channel members 33 can be secured to the walkway beams in any desired manner. As illustrated, they are bolted thereto by means of suitable bolts 34.

The lower race of a second anti-friction thrust bearing 35 is mounted in the upper extremity of the flange collar 25 about the shaft 24. The weight of the walkway beams 32 is transmitted to the upper race of the second thrust bearing 35 through the medium of a bearing plate 36 extending between the cross channels 33 and secured thereto by means of suitable attachment bolts 37. If desired, the walkway beams 32 may continue entirely across the tank, as indicated in broken line at 32' in FIG. "1, or they may terminate at any desired point beyond the supporting column 21. In any event, they can be relatively light beams since the weight of the supported structure is carried by the supporting column 21.

A conventional speed reduction gear assembly 38 is mounted on the walkway beams 32 from which the drive shaft 24 extends. The power is transmitted to a drive shaft 40 on the reduction gear assembly 38, in any conventional manner, to rotate the tubular sludge shaft 27 at the desired speed. It will be noted that the stilling bafile 16 about the flocculation zone 17 is also supported or suspended from the walkway beams 32. upon suitable hangers 51 so that the entire weight of the bafile 16 and the paddles 19 will also be carried by the second thrust bearing 35.

The flocculation arms 20 extend fixedly and radially from a suspended cylindrical skirt 41. A ring gear 43 is aflixed to and surrounds the upper extremity of the skirt 41 and supports the skirt 41 in a gear housing 44 which is closed at its top by means of a cap plate 50. Suitable bolts 45 clamp the cap plate 50 to the gear housing 44 and also secure both to the walkway beams 32. The skirt 41 is rotated in any desired manner, such as through the medium of a spur gear 46 mounted on a flocculation drive shaft 47 which can be connected to any conventional driving mechanism in any suitable manner.

The entire weight of the flocculation arms 20, the skirt 41 and its driving mechanism is supported from the walkway beams 32 and they, in turn, are supported upon the second thrust bearing 35, which, in turn, is supported on the collar 25 which transmits the weight through the first thrust bearing 23 to the supporting, column 21 so that the walkway beams 32 have very little weight to carry and the span of the beams is much shorter than in the conventional structure.

The above structure provides a beam weight and cost of about one-fourth that of a diametric self-supporting truss and about one half that of a radial, column-supported mechanism carrying beam.

While a specific form of the improvement has been described and illustrated herein, it is to be understood that the same way be varied within the scope of the appended claims, without departing from the spirit of the invention.

Having thus described the invention what is claimed and desired secured by Letters Patentv is:

1. In a clarification tank, an axially-positioned fixed vertical supporting column; a concentrically positioned thrust bearing mounted on the top. of said column; a drive shaft rotatably mounted in and in vertical axial alignment with said bearing; a collar element fixedto said drive shaft and supported by said thrust bearing; rake arms extending from said collar element; a second thrust bearing surrounding said drive shaft and bearing on said collar element; shaft driving means co-axial with said column and supported by said second thrust bearing and connected with said drive shaft to drive the latter and thereby cause said rake arms to revolve about said column; and rotation preventing means acting to prevent rotation of said shaft driving means, said rotation preventing means comprising a beam structure of less length than the diameter of said tank extending from and being stationarily mounted on one side of said tank, the axial portion of said structure being mounted on and supported by said second thrust bearing, said shaft driving means being mounted on said beam structure.

2. Means for supporting a plurality of rake arms as described in claim 1 having in combination therewith a plurality of flocculation arms, means suspending said flocculation arms from said beam structure whereby said arms may rotate about said column, gear means secured to said beam structure to rotatably drive said flocculation arms; a stilling baffle suspended from said beam structure about said flocculation arms, the weight of said beam structure with its associated baffle and gear means being supported by said second thrust bearing, and the weight of said second thrust bearing with its superimposed load and the weight of said collar element and attached rake arms being transmitted by said first thrust bearing to said column.

References Cited in the file of this patent UNITED STATES PATENTS 1,717,764 DOlier June 18, 1929 2,268,475 Darby Dec. 30, 1941 2,723,760 Talbot Nov. 15, 1955 

